Last night I edited the default-display-manager file and changed my default display manager from lightdm to lightdm-gtk-greeter. Then I edited the lightdm-gtk-greeter config file and changed the wallpaper. Now, when I reboot the computer I get a whole string of messages where the computer is booting up but it freezes and won't boot into the system. It just hangs there. How do I get back into my system? I'm running Xubuntu 12.04 64-bit.

If you able to go to recovery console by grub and bypass xinit you could change to gdm or whatever you like. otherwise try CTRL+C and repeat it as often as you could before lightdm displays in a short sequence while booting may be it helps.
–
JoshAug 31 '13 at 13:10

2 Answers
2

Ok, this is what did the trick for me. I received this advice from someone else. When the system hung up I pressed Ctrl-Alt-F1 and got to a virtual terminal. Then, I issued the command sudo dpkg-reconfigure lightdm. That reset my display manager back to lightdm and I was able to sign in as normal. Everything works fine now.

You can give it a try, if you are using internet connection using Wired LAN then these may work for you:

Installing GDM (a display manager like lightdm) can fix your problem:

Method 1:

This method works when you are able to go to at least the command line interface.

Press CTRL+ALT+F1 or CTRL+ALT+F2 when your system starts and starts freezing or black screen appears. It will let you to use Command Line Interface. Then login using your username and password, and try following commands:

Then login in save mode or Recovery Mode. After a lot of text displayed in black

screen one window will come which list some options. First go to option Grub, it
will mount your file system in read/write mode. Then chose root option in order
to login as root. Then go to the pendrive where you saved the deb file. The drive
should be listed in in /media. I am assuming that you saved the file in gdm
directory inside pendrive (pendrive is the name of your pendrive)

# cd /media && ls

(which will list your pendrive if you don't get pendrive
folder then go to Mount Pendrive Section at last, then come back here and continue to next step.)

# cd /media/pendrive/gdm

(go to gdm directory where .deb file is saved.)

# dpkg -i *.deb

(installing gdm)
While installing gdm one window will come which will ask your to chose lightdm or gdm
from the list. Chose gdm. If this window doesn't appear then try following command:

# dpkg-reconfigure lightdm

(chose gdm) Then finally execute following command:

# reboot (reboot your system)

Mount Pendrive Section

Mounting pendrive while working in recovery mode.

Run this command:

# fdisk -l

Find your device in the list, it is probably something like /dev/sdb1. Then execute other commands one by another: